docs: def _drop_server(self, server, message):
          """
          Drop server from active list and adds it to the inactive ones.
          """
          try:
              self._active_servers.remove(server)
          except ValueError:
              pass
          else:
              heapq.heappush(self._inactive_servers, (time(), server, message))
              logger.warning("Removed server %s from active pool", server)
  
          # if this is the last server raise exception, otherwise try next
          if not self._active_servers:
              raise ConnectionError(
                  ("No more Servers available, "
                   "exception from last server: %s") % message)